Survey

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Elementary algebra wikipedia, lookup

History of algebra wikipedia, lookup

Equation wikipedia, lookup

Transcript
```2-1A Writing Equations
Algebra 1
Glencoe McGraw-Hill
Linda Stamper
In Chapter 1 you translated phrases. Phrases are
translated into mathematical expressions. Sentences are
translated into equations or inequalities.
Phrase
The sum of 6 and a number
6 + n
Sentence The sum of 6 and a number
is fifteen.
6 + n = 15
Sentence Seven times a number
is less than 50.
7n < 50
When choosing a variable for an unknown, it may be helpful
to select a Sentences
letter that must
relates to the unknown value (for
example: let have
a represent
a verb!age).
When you translate from English to math, you must first
determine whether the given problem is an expression
(phrase) or a sentence. How
do you know
the difference?
A sentence
will have
a verb.
Some verbal expressions that suggest the equal sign are:
is
is as much as
is the same as
is identical to
3
times a number is 36.
= 36
3n
Identify the verb. Write the equal sign. Translate
the expression to the left of the verb. Translate the
expression to the right of the verb. The equal sign is
like a brick wall – nothing crosses to the other side.
Translate each sentence into an equation.
21 decreased by a number is 7.
21  n = 7
Twelve is the sum of nine and a number.
12 = 9  n
15 less than a number is 56.
n  15 = 56
Five times the number a squared is three times
the sum of b and c.
5a2 = 3 (b + c)
The verb is where you write the equal sign.
The equal sign is like a brick wall –
nothing crosses to the other side.
Example 1 Translate each sentence into an equation.
a. Four times n is the difference of 30 and n.
4n = 30 - n
b. Nine increased by a number is five squared.
9 + n = 52
c. Ten less than a number is fifty.
n – 10 = 50
d. The sum of two and a number is 9.
2+n=9
e. A number decreased by five is four squared plus six.
n - 5 = 42 + 6
f. The sum of a number and six, divided by three is eight.
n6
8
3
Example 2 Translate each sentence into an equation.
a. Fifteen more than z times 6 is y times 2 minus eleven.
6z + 15 = 2y - 11
b. Seven increased by a number is 21.
7 + n = 21
b
c. A number b divided by three is six less than c.  c  6
3
d. Twenty-seven times k is h squared decreased by 9.
27k = h2 - 9
e. Nine times a number subtracted from 95 equals 37.
95 – 9n = 37
f. Two plus the quotient of a number and 8 is 16.
n
2   16
8
A formula is an algebraic equation that relates two or
more quantities.
Example 3 Translate each sentence into a formula.
a. The perimeter of a rectangle equals two times the
length
=
length plus two times the width.
width
P = 2l + 2w P = 2l + 2w
length
b. In a right triangle, the sum of the squares of the
measures of the legs, a and b, is equal to the square of
(hypotenuse)
the hypotenuse c.
(leg)
c
a2 +
b2
=
c2
a
(leg)
b
c. The perimeter of a triangle is side a plus side b plus
side c.
P = a+ b + c
width
2-A2 Pages 74-76 #13-18,23-26,35-36,50-51,57-68.
```
Related documents